One
company that many of our readers are likely unfamiliar with is DisplayLink. We
received a press release from them prior to CES and decided to stop by and see
a demonstration of their products. The concept is pretty simple, and it's not
something everyone will benefit from, but if you've ever wanted to add a second
display without worrying about upgrading video cards you'll appreciate what
they've created. DisplayLink provides technology that allows you to hook up
additional displays via a standard USB connection. DisplayLink also has
partners like Samsung where the technology is integrated directly into a
display - a 19" LCD was released in June with this functionality and more
offerings are planned.

If
you're quick at math, you're probably already wondering how they manage to deal
with the limited bandwidth. DisplayLink says that they're currently doing well
with around 200Mbit of throughput, though they are able to scale down quality
if necessary. What they have is a software display driver, and they only
transmit actual updates over the connection. Ideally, everything is done with
lossless quality, but the technology is intelligent enough to deal with reduced
bandwidth. Lossy compression comes next, followed by a reduction in color
depth, and finally frames are dropped if necessary.

They
demonstrated systems running anywhere from one to many additional displays,
with static images, animated desktops (running a script), and streaming video
content. Depending on the intensity of the content being shown, the experience
ranged from very smooth to slightly choppy at times, but for desktop usage
patterns we definitely didn't see anything unacceptable. Video streaming even
worked reasonably well at moderate resolutions, with full screen 1680x1050
showing some definite loss in quality.

Besides
wired USB connections, DisplayLink works with other companies to provide
wireless display connectivity. DisplayLink uses WiMedia as the physical UWB (Ultra
Wide-Band) communications layer, and on top of that they run the Wireless USB
protocol. This isn't something where you'll be able to transmit your display
content throughout a large house, but they are working at providing wireless
display support within the same room (approximately 15 feet). Throughput within
the same room is getting around 120Mbit with the potential for up to 200Mbit.
Theoretically, 480Mbit (Wireless USB) is possible, but just like regular USB
and WiFi you can't actually get the full bandwidth. Note that WiMedia's maximum
bandwidth is #ff0000, but most likely they won't get more than 300Mbit in
ideal circumstances. They told us that 802.11x WiFi support didn't work out
well due to inconsistencies in throughput - it's not uncommon to get 100Mbit
one moment and 30Mbit the next with 802.11n, for example, so they turned to
WiMedia and found that the bandwidth consistency was much better.

Resolution
support is currently somewhat limited, though more than sufficient for most
users. They currently support 1600x1200 maximum (or 1280x1024 on a lower end
chip). They are working at providing 1920x1200 with a new chip, which is due to
be released later this year. While it's still in beta status, they did provide
a live demonstration of 1920x1200 output. Another upcoming development they
demonstrated is that Intel has been extremely impressed with their work so far,
and since Intel doesn't have any discrete graphics market to protect they
worked with DisplayLink to integrate the necessary code directly into some test
GMA X3000 drivers. With the improved performance brought about by this change,
they were able to demonstrate 720p content with little if any loss in quality.

For
our greedy readers (Ed: you know who you are!), you're
probably wondering how far you can push this technology in terms of display count.
As an example of the extreme end of the spectrum, they had a demonstration of a
laptop running six displays (via a single connection to a USB hub). There was
definitely a bottleneck in terms of bandwidth in this configuration, but if you
aren't planning on streaming video to multiple displays you could easily have
multiple monitors all displaying different content. Remember: as long as
nothing changes on the display in question, no bandwidth is used. So if you
wanted to have a second (or third or fourth…) LCD showing a static document
while you work on the main display, this would be a perfect solution. This
particular configuration was consuming about 100MB of memory for the
DisplayLink software, ~33% of the CPU time (on a Core 2 Duo T7100), while
Windows Media Player used another 15-20% to play a video on one of the
displays.

Let's
get a few other things out of the way now by explaining what DisplayLink does
not do very well. For one, gaming support that requires a discrete GPU is
basically out of the question. The DisplayLink adapter is a virtual display
device with its own resources. It works well enough in Windows - XP and Vista
are supported - but certain content obviously has more difficulty running well.
Video streaming was demonstrated and it worked well enough, but in full-screen
mode at 1680x1050 you can definitely see some choppiness and compression
artifacts. We tried to get a demonstration of doing two simultaneous video
streams (on Windows Vista - XP only supports overlay mode on one screen at a
time, so it's not possible there), but we were unable to do so in the time we
had at their suite. However, we do have some hardware to test, so we will look
at other options in the near future. DisplayLink also has a version of their
software scheduled to come out for OS X in the next few months.

The
primary target market appears to be businesses, particularly those looking to
improve productivity by adding a second display. However, there are certainly
many others that would be interested in using this sort of technology. We will
try to get additional information on pricing and availability for the various
products.

Well I know that I have run 3 h264 encoded videos through MPC (Media Player Classic) on 3 monitors simultaneously (2 connected via 1 graphics card, 1 connected by a second card), with output set to "system default", under Windows XP, so it's easily possible. Reply